Akio Kanazawa

Effects of dietary lipids, fatty acids, and phospholipids on growth and survival of prawn (Penaeus japonicus) larvae

Abstract The effects of lipids, fatty acids, and phospholipids on growth and survival of larvae of the prawn, Penaeus japonicus , were examined using purified diets containing carrageenan as a binder. P. japonicus larvae did not metamorphose to post-larvae and died in 7 days when fed the diets containing no phospholipid. Growth and survival rate of the prawn larvae were improved by the addition of soybean phosphatidylcholine (PC) to the diets containing 18:1ω9 and essential fatty acids (EFA), or pollack liver oil (PLO) as lipid sources. These results suggest that P. japonicus larvae probably require dietary sources of some phospholipids for growth and survival. The efficacy of phospholipids in improving growth and survival varied with the kinds and sources of phospholipids. Bonito-egg PC, soybean PC, and soybean phosphatidylinositol (PI) had a high efficacy, whereas chicken-egg PC was ineffective. Ovine-brain phosphatidylserine, bonito-egg phosphatidylethanol-amine (PE), and ovine-brain PE improved slightly growth and survival of P. japonicus larvae. The PC and PI containing high proportions of ω6- and ω3-fatty acids as constituents were thought to be effective in improving growth and survival of the prawn larvae. The optimum level of soybean PC for P. japonicus larvae varied with the kinds of coexistent dietary lipids. The best growth and survival were attained on the diets containing 6.0% soybean PC when 18:1ω9 and 1.0% highly unsaturated fatty acids were used as basal lipids. But the inclusion of 3.5% soybean PC was enough to attain optimum growth and survival when PLO was used as the lipid source. The present study did not give a clear picture of the EFA requirements of P. japonicus larvae, although they seemed to vary with dietary phospholipid levels.

Effects of docosahexaenoic acid and phospholipids on stress tolerance of fish

Abstract The effects of dietary docosahexaenoic acid (DHA, 22:6(n − 3)) and phospholipids (soybean lecithin) on the stress tolerance of marine fish, i.e., larval red sea bream (Pagrus major) and juvenile marbled sole (Limanda yokohamae), were investigated using 20–30 days feeding trials. The tolerance of these two marine fish to various stress factors such as changes in water temperature and salinity, and exposure to low dissolved oxygen and to air were determined. Dietary DHA and soybean lecithin were effective in increasing the tolerance of red sea bream and marbled sole to the various stress conditions.

Effects of coating and encapsulation of crystalline amino acids on leaching in larval feeds

Abstract Three types of microparticulate diets for marine larval fish were tested to improve retention of added amino acids after immersion in water. These particle types included microbound, microcoated, and microencapsulated particles. Binding crystalline amino acids to alginate, carrageenan or zein microparticles gave poor results, with leaching of 80–90% of the crystalline amino acids within minutes after immersion in water. Coating microbound diets or crystalline amino acids with tripalmitin had little effect on the retention of crystalline amino acids. Microencapsulation of crystalline amino acids within protein-walled capsules gave better results, with capsules retaining up to 60% of some crystalline amino acids after 2 min in water. The best results were obtained by encapsulating crystalline amino acids within lipid-walled capsules. Retention was further improved by including 2% (w/w) Span 85, a surface-active agent, in the lipid wall of the capsules. With this technique, leaching was reduced to 1.4% when capsules were suspended for 2 min in buffered water (pH 8.5). Feeding studies with olive flounder ( Paralichthys olivaceus ) indicated that larvae older than 20 days could break tripalmitin-walled capsules. Lipid-walled capsules show promising potential for use in nutritional studies with marine fish larvae.

Dietary value of several proteins and supplemental amino acids for larvae of the prawn Penaeus japonicus

Abstract The dietary value of several proteins and supplemental amino acids for larval prawn ( Penaeus japonicus ) was examined using artificial diets containing carrageenan as a binder. As a nitrogen source, casein-gelatin (3:1), casein, and white fish meal had superior nutritive values to gelatin, egg albumin, and an amino acid mixture approximating the composition of casein. The supplementation of a casein diet with crystalline L-arginine HCl improved its nutritive value to that comparable to live food (control). In a subsequent experiment, about half the casein in the casein-based diets was replaced with a mixture of crystalline amino acids, either coated or uncoated with a nylonprotein membrane, and balanced to approximate the amino acid pattern to that of prawn larval whole body protein. Diet containing crystalline amino acids gave survival rates and growth indices equal to or higher than the control group receiving live food. This indicates that prawn larvae are probably able to utilize an amino acid mixture as a partial protein substitute in contrast to juvenile prawns which lack this ability.

Requirements of juvenile marine shrimp, Penaeus monodon (Fabricius) for lysine and arginine

Abstract Feeding experiments were conducted using amino acid test diets to determine the dietary requirements of juvenile Penaeus monodon for lysine and arginine. Two sets of the test diets were prepared. The natural protein was supplied by casein and gelatin. Crystalline l -amino acids were added to provide an amino acid profile similar to shrimp muscle protein except for the test amino acid. One set of experimental diets contained graded levels of lysine at 1.18–3.28% of the diet and another set contained arginine at 0.6–3.0% of the diet. The amino acid mixture was pre-coated with carboxymethylcellulose (CMC) and diets were further bound with CMC, cornstarch, and K–carrageenan to prevent leaching losses of amino acids. Shrimp postlarvae, PL20, with mean weight of 21±0.5 mg, were randomly distributed at 10 shrimp per tank in 40-l fiberglass tanks and reared on the diets for 50–56 days. Growth, survival and feed conversion efficiency were determined at termination of feeding trials and signs of nutritional deficiency noted. Lysine and arginine requirements were determined from relationships between weight gains and dietary lysine and arginine levels as analyzed by the broken-line regression method. The requirement of juvenile P. monodon for lysine was estimated to be 2.08% of the diet or 5.2% of dietary protein while the requirement for arginine was 1.85% of the diet or 5.3% of dietary protein. This information is crucial in formulating cost-effective practical diets for juvenile tiger shrimp.

Studies on the presentation of artificial diets for rearing the larvae of Penaeus japonicus Bate

Abstract The preparation of microencapsulated diets for rearing the larvae of Penaeus japonicus is described. Once the correct microcapsule size and feeding concentration had been determined, experiments showed that survival rates of 50% to post-larva were possible. Comparative experiments using artificial diets in the form of free particulates indicate that survival rates may be even higher (66–68%) on these diets providing precautions are taken to avoid bacterial blooms. Further investigations revealed that microencapsulated semi-defined diets may be used to determine the nutritional requirements of Penaeus larvae.

Methionine requirement of juvenile tiger shrimp Penaeus monodon Fabricius

Abstract An 8-week feeding trial was conducted to determine the dietary requirement of postlarval Penaeus monodon for the sulfur-containing amino acid methionine. Shrimp postlarvae (mean weight 21 ± 0.3 mg) were reared in 40-1 fiberglass tanks in a flow-through seawater system. Test diets (37% protein and 360 kcal per 100 g diet) were formulated containing casein-gelatin as protein sources and supplemented with crystalline amino acids to simulate the amino acid pattern in shrimp tissue protein except methionine. The diets contained graded levels of methionine at a range of 0.72–1.12% of the diet or 2.0–3.0% of protein. In diet preparation, the crystalline amino acids were pre-coated with carboxymethylcellulose (CMC) to reduce leaching. Diets were further coated with CMC, cornstarch, and κ-carrageenan to improve water stability and the diet pH was kept at 7.0–7.2 by neutralization with 6N NaOH. Shrimp were fed the diets at 25–30% of their biomass thrice daily. At termination of the feeding experiment, various parameters including growth, survival, and feed conversion efficiency were determined and nutritional deficiency signs noted. The methionine requirement was determined from the relationship between weight gain and dietary methionine level using the broken-line regression method. The requirement of P. monodon postlarvae for methionine was 0.89% of the diet or 2.4% of protein. In a diet containing 0.41% cystine, the total sulfur amino acid requirement (methionine + cystine) would be 1.3% of the diet or 3.5% of protein. This requirement is slightly lower than the methionine level present in shrimp tissue protein.

The effect of dietary protein content on growth, digestion efficiency and nitrogen excretion of juvenile kuruma prawns, Penaeus japonicus.

Abstract The effect of dietary protein contents on growth, digestion efficiency and ammonia and urea excretion of juvenile kuruma prawns, Penaeus japonicus , was investigated. Isocaloric, crab-protein-based, dry diets containing five protein contents (21 to 61%) were formulated and fed to prawns (initial mean wet wt 0.4 g) at a ration level of 6% body weight per day for 30 days. At the end of the trial, intermolt-staged prawns (0.5 to 2.0 g wet weight) were used for determination of digestion efficiencies for dry matter and protein, and ammonia and urea excretion rates. Weight gain, specific growth rates (SGR) and feed conversion efficiency (FCE) values for prawns fed diets containing 21 and 31.4% protein were significantly lower than those for prawns fed diets containing higher protein contents. There was no significant difference in weight gain, SGR and FCE values among prawns fed the 41.6, 50.3, and 60.7% protein diets. Digestion efficiencies for dry matter and protein ranged from 73 to 77% and 93 to 96%, respectively. After a 1-h feeding period, cumulative ammonia excretion over a subsequent 5-h period increased with increasing dietary protein content, and ammonia excretion reached a peak within the first 3-h period in all treatment groups. In contrast, ammonia excretion rates of prawns initially fed on diets with different protein contents then starved for 24 h, were constant at about 10 μ g/g h −1 , indicating that a 24-h starvation period eliminated differences in ammonia excretion rates due to variation in dietary protein content. Urea excretion rates were much lower than ammonia excretion rates in this species. Results indicated that 42% dietary protein sustained maximum growth of kuruma prawns under the conditions employed in this study, and that there was a positive correlation between SGR and ammonia excretion for juvenile P. japonicus .

Nutritional value of dietary cholesterol and other sterols to larval prawn, Penaeus japonicus Bate

The nutritional value of 11 sterols to larval prawn, Penaeus japonicus, was examined using defined, artificial diets containing carrageenan as a binder. Growth and survival of the prawn larvae fed on a diet with 1.0% cholesterol, 6.0% pollack liver oil, and 3.0% soybean lecithin as lipid sources were similar to those of the control group receiving both Chaetoceros gracilis and Artemia salina nauplii. A sterol-free diet resulted in poor survival and slight retardation of larval development. These results show that the prawn larvae require dietary sources of cholesterol or other sterols as indispensable nutrients. Cholesterol had the highest dietary value among the sterols examined in terms of promoting growth and survival. Ergosterol and 24-methylenecholesterol had a similar dietary value to that of cholesterol. 24-Methylcholesta-5,22-dienol, isofucosterol, and 7-cholestenol also effectively supported growth, whereas stigmasterol, β-sitosterol, 22-dehydrocholesterol, fucosterol, and lanosterol promoted growth weakly or not at all. Isofucosterol, β-sitosterol, and 22-dehydrocholesterol increased the rate of survival of the prawn larvae slightly, but stigmasterol, fucosterol, 7-cholestenol, and lanosterol were ineffective. The results of the present study suggest that P. japonicus larvae are probably incapable of de novo sterol synthesis but may be able to dealkylate some C28 and C29 sterols to cholesterol, which is the most effective sterol.

Biosynthesis of sterols in the lobster, Panulirus japonica, the prawn, Penaeus japonicus, and the crab, Portunus trituberculatus

Abstract 1. 1. In the present study, the sterol-synthesizing abilities of the lobster, Panulirus japonica, the prawn, Penaeus japonicus, and the crab, Portunus trituberculatus, were investigated by using acetate-1-14C. 2. 2. It was found that the three species of marine crustaceans are capable of synthesizing fatty acids and some non-saponifiable materials. However, under the present experimental conditions, these animals did not incorporate acetate-1-14C into sterols.